Arrangement for continuously determining the density of a web of fiber sliver

Abstract

An arrangement for continuously determining the density of an elongated strip-shaped web of fiber sliver in the course of a spinning process in order to generate control signals for use in controlling the operation of machine elements operative for equalizing the distribution of the fiber sliver includes two of stepped rollers which together delimit, at a their nip region, a confining space for the passage of the fiber sliver web therethrough. One of the rollers is mounted on a support for rotation about a stationary axis and is driven in rotation, while the other roller is mounted on the support for free rotation about another axis which is parallel to the stationary axis and defines an imaginary plane therewith, as well as for movement along the imaginary plane against a spring force away from the one roller, so that the fiber sliver is compressed and moves the other roller to a greater or lesser degree away from the one roller as it passes through the confining space, depending on its density. A contactless proximity sensing element is arranged along the imaginary plane and has a sensing surface which faces a portion of the peripheral surface of the other roller so as to detect the extent of displacement of the other roller relative to the one roller and issue an electric signal representative of the detected value.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims; we claim: 
     
       1. An arrangement for continuously determining the density of an elongated web of fiber sliver, comprising a support; a pair of rollers having respective peripheral surfaces which receive the elongated web between themselves and including a driven roller mounted on said support for rotation about a stationary axis and an additional roller mounted on said support for rotation about an additional axis which is parallel to said stationary axis and defines an imaginary plane therewith, and for movement along said imaginary plane toward and away from said driven roller; means for urging said additional roller toward said driven roller to confine the web between said peripheral surfaces of said rollers and to frictionally entrain said additional roller for rotation about said additional axis; and means for sensing the extent of movement of said additional roller along said imaginary plane and thus the instantaneous density of the fiber sliver web confined between said peripheral surfaces of said rollers, including a contactless sensing element having a sensing surface which is situated substantially at said imaginary plane and faces said peripheral surface of said additional roller to defined therewith a gap having a size which varies proportionately to said movement of said additional roller along said imaginary plane, said sensing element being operative for measuring said varying size of said gap. 
     
     
       2. The arrangement as defined in claim 1, and further comprising means for so mounting said sensing element and said additional roller on said support that said size of said gap and thus the measuring results obtained from said sensing element are virtually independent of changes in the temperature of the arrangement. 
     
     
       3. The arrangement as defined in claim 2, wherein said mounting means for said sensing element and for said additional roller includes support elements which extend substantially normal to said imaginary plane. 
     
     
       4. The arrangement as defined in claim 3, wherein said sensing element is arranged next to said driven roller. 
     
     
       5. The arrangement as defined in claim 4, wherein said driven roller is mounted on a shaft which is centered on said stationary axis; and wherein said shaft and that one of said support elements which supports said sensing element are arranged one after the other as considered in the axial direction of said shaft. 
     
     
       6. The arrangement as defined in claim 5, wherein said one support element has a plane of symmetry which coincides with an additional imaginary plane which includes said stationary axis and extends normal to said imaginary plane. 
     
     
       7. The arrangement as defined in claim 3, wherein said support elements for said additional roller are leaf springs each having a predetermined width and so arranged with their widths extending parallel to said additional axis of said additional roller that the movements of said additional roller occur in a frictionless manner. 
     
     
       8. The arrangement as defined in claim 3, wherein said urging means includes respective springs each so arranged at one axial side of said additional roller that the force transmission therefrom occurs in a frictionless manner. 
     
     
       9. The arrangement as defined in claim 1, wherein said rollers of said pair are constructed as stepped rollers.